Dr. Conrad Murray's involuntary manslaughter trial took a shocking turn on Wednesday morning as the defense announced it was abandoning one of its main points -- that Michael Jackson had accidentally killed himself by swallowing Propofol.

Testimony from two of the prosecution's witnesses, Dr. Alon Steinberg, a cardiologist, and Dr. Christopher Rogers, the doctor who declared Jackson's death a homicide, put big holes in that theory.

The defense could still argue that Jackson injected the drug, but Rogers testified that he thinks that is unlikely. Find out why below.

The defense has argued that Murray was not negligent because he only left MJ alone for "two minutes to use the bathroom" after administering Propofol.

Rogers pointed out that, if that is true, that would not have been enough time for MJ to self-administer Propofol, which the defense has argued is what killed Jackson.

He also pointed out that Jackson would have had to wake up from his Propofol-induced sleep (Conrad said Jackson was sleeping when he left the room), and then given himself the drug.

Jackson's death was the result of an overdose of Propofol. Rogers said what is more likely is that Murray gave Jackson several doses of Propofol over a few hours without monitoring the doses.

In addition, the prosecution is gaining ground on their argument that Murray was grossly negligent -- see what Dr. Steinberg testified after the jump.

Steinberg's testimony:

Steinberg said he had reviewed the case and felt Murray was (as the prosecution has been trying to prove) grossly negligent.

Steinberg said Propofol should only be used in hospitals and never for sleep, and that he'd never heard of it being used for sleep.

He said Murray lacked basic equipment and an assistant -- both necessary in case of an emergency. He also failed to document MJ as a patient (no notes on his care.)

He said Murray's biggest act of negligence was not immediately calling 911. He called Murray's behavior bizarre. He said Murray should have given Jackson an antidote called Flumazenil, not given him chest compressions.

He said Murray's actions "directly contributed to the untimely death of Michael Jackson" -- that for each moment he did not call 911, it increased the odds of Jackson's death.

The prosecution only has a few witnesses left to call in the LA trial, which is in its third week.